Malathion

Malathion is a thiophosphate prodrug that is converted to active phosphate derivatives in animals and plants. These active metabolites inhibit acetylcholinesterase by binding covalently to its esteratic site, preventing the enzyme's rapid reactivation. This leads to an accumulation of acetylcholine, causing prolonged cholinergic effects.

Adult

For scabies, apply twice, one week apart, to the whole body including scalp, neck, face, and ears, paying particular attention to webs of fingers/toes and under nails. Reapply to hands if washed. For hyperkeratotic scabies, 2-3 applications on consecutive days may be required. For head lice, apply 0.5% lotion, then reapply in 9-10 days.